Final answer:
Ribosome subunits comprise several rRNA molecules and up to 70 different proteins, essential for protein synthesis. Prokaryotic cells like E. coli can contain tens of thousands of ribosomes, while eukaryotic cells have nucleoli specialized for rRNA synthesis and ribosome assembly.
Step-by-step explanation:
These ribosome subunits are made up of several ribosomal RNA (rRNA) molecules and as many as 70 different proteins. Ribosomes are critical for protein synthesis as they assemble amino acids into proteins during this process. Each ribosome is a complex macromolecule that includes both structural and catalytic rRNAs and many distinct polypeptides. In prokaryotic cells like those of E. coli, a single cell contains between 10,000 and 70,000 ribosomes. Eukaryotic cells have specialized structures, called nucleoli, which are dedicated to the synthesis and assembly of rRNAs, a key component of ribosomes. It's also important to note that prokaryotic ribosomes are referred to as 70S, composed of a 50S large subunit and a 30S small subunit, while eukaryotic ribosomes found in the cytoplasm and rough endoplasmic reticulum are larger, at 80S, composed of a 60S large subunit and a 40S small subunit.